He said: “I parked up as I normally would to let my dog out of the car and he started going crazy.

“He ran over to what I thought was a load of stones and started sticking his head right into it.

“As I got closer I realised that the pile was actually a load of shells. It smelt really bad, like rotting fish.”

“There’s absolutely thousands of them, I couldn’t believe it when I saw it.”

A huge pile of shells have been found on a Teesside nature reserve

Initially, council workers at the scene were confused as to why or how the shells had ended up there but the Tees Valley Wildlife Trust has since confirmed they are being used for a new habitat project.

A spokeswoman for the trust said: “We are carrying out work to improve habitat for wading birds, on our Bowesfield South Holme nature reserve. Birds such as lapwing, redshank, curlew and golden plover will benefit.